A stone called simply the “Indian Stone,” and said to be light and porous, is noted by pseudo-Aristotle, and to it is attributed the power to relieve those suffering from dropsy, by drawing the water to itself. If weighed after having been applied to the patient, the stone was found to have increased in weight in proportion to the amount of water absorbed, and when it was placed in the sun, water of a yellowish hue exuded, until, finally, the stone resumed its original appearance and weight.[326] Another and perhaps earlier authority gives the name “toad-stone” to this material.[327] [Illustration: BVFONITES Toad-stones. Natural concretions of claystone and limonite. From Mercati’s “Metallotheca Vaticana,” Romæ, 1719. ] The toad-stone was not only an antidote for poisons, but was also thought to give warning of their presence by becoming very hot. To fully profit by this strange quality, the wearer of such a stone was advised to have it so set in a ring that it would touch the skin; in this way he would be sure to have timely notice, if any poisoned food or drink were offered to him.[328] The writer who mentions this adds the following tale of the discovery of a toad-stone: A clerk once found a toad which had a round knob on its head, wherefore he thought that there must be a toad-stone. So he took up the toad and tied it firmly in the sleeve of his coat. When he returned from the fields and searched for the toad he found it not, although the sleeve of his coat was tightly bound below and he could not discover any opening through which the creature could have passed. This shows us that it is a great help to prisoners in jail. Another early authority, Thomas de Cantimpré, says of the toad-stone: If one take the stone from a living and still quivering toad a little eye can be seen in the substance; but if it be taken from a toad that has been some time dead, the poison of the creature will have already destroyed this little eye and spoiled the stone. If the toad-stone be swallowed at meal-time it passes through the system and carries off all impurities.[329] Here the substance may have been one of many concretionary materials,—bauxite, impure pearls, concretionary limestone, stalagmite, or even the eye-stones from the crawfish; indeed, any material, white or gray, that had a semblance to a toad color, and was then sold by the vendor of charm stones as coming from a toad’s head. The great Erasmus (1465–1536) made a pilgrimage to the famous shrine of the Virgin in the church at Walsingham, in Kent. In his description of what he saw there he expressly notes a wonderful toad-stone: